The present invention refers to obtaining, maintaining and/or adjusting temperature gradient and/or differential in between two different domains of a plate and having different temperatures.
Growth of gaseous phase crystals and experiments related thereto involve e.g. HgJ.sub.2. Experiments of this kind pose high demands on the thermal boundary conditions of the system. During the running of the experiment such as the growing a crystal relevant crystal dimensions vary from a few mm to several cm. Thus one can readily see that the relevant thermal boundary conditions should also continue to "grow along". Specifically that means that a cooled area on which a crystal grows has to be continuously enlarged while on the other hand the environment should be maintained isotropically on a somewhat higher temperature level. To the best of our knowledge adequate solutions to that problem other than "stop gap measures" are not known.